Kawama Raki, Takahashi Katsuki, Ikifune Haruki, Tozawa Hironoshin, Obata Takafumi, Ito Ryo, Hojo Tatsuya, Wakahara Taku
Faculty of Health and Sports Science, Doshisha University, Kyoto, JAPAN.
Graduate School of Health and Sports Science, Doshisha University, Kyoto, JAPAN.
Med Sci Sports Exerc. 2024 Dec 1;56(12):2349-2361. doi: 10.1249/MSS.0000000000003516. Epub 2024 Jul 15.
Resistance training may be empirically believed to increase passive muscle stiffness. Meanwhile, a recent study showed that the passive stiffness of a specific hamstring muscle acutely decreased after eccentric-only resistance exercise at long muscle lengths with a long contraction duration (LL). To extend this finding, the present study investigated the chronic effects of eccentric-only resistance training with LL at different weekly frequencies on the passive stiffness of the biarticular hamstring muscles.
Thirty-six healthy young males were assigned into two training groups with two and three weekly sessions (W2 and W3; n = 12, respectively) and a control group (CON; n = 12). The participants in both training groups performed eccentric-only stiff-leg deadlift at 50%-100% of exercise range of motion (0% = upright position) with 5 s per repetition for 10 wk. Before and after the intervention period, the shear moduli of the biarticular hamstring muscles, maximal voluntary isometric torque of knee flexion, and volumes of the individual hamstring muscles were measured.
In W3, the shear modulus of the semimembranosus (-11.4%) significantly decreased, whereas those of the other biarticular muscles did not change. There were no significant changes in the shear moduli of the biarticular hamstring muscles in W2 or CON. The isometric torque (20.3% and 26.2%, respectively) and semimembranosus volume (5.7% and 7.4%, respectively) were significantly increased in W2 and W3.
Passive stiffness of a specific muscle could be chronically decreased when eccentric-only resistance training with LL is performed at a relatively high weekly frequency with a high total training volume. Our training modality may be a promising strategy for decreasing passive muscle stiffness while increasing muscular strength and size.
从经验上看，抗阻训练可能被认为会增加肌肉的被动僵硬度。与此同时，最近一项研究表明，在长肌肉长度和长收缩持续时间（LL）下进行仅离心的抗阻运动后，特定绳肌的被动僵硬度会急性降低。为了拓展这一发现，本研究调查了在不同每周频率下进行LL仅离心抗阻训练对双关节绳肌被动僵硬度的长期影响。
36名健康年轻男性被分为两个训练组，分别为每周训练两次和三次（W2和W3，每组n = 12）以及一个对照组（CON，n = 12）。两个训练组的参与者在运动范围的50%-100%（0% = 直立位）进行仅离心的直腿硬拉，每次重复5秒，共进行10周。在干预期前后，测量双关节绳肌的剪切模量、膝关节屈曲的最大自主等长扭矩以及各绳肌的体积。
在W3组中，半膜肌的剪切模量显著降低（-11.4%），而其他双关节肌肉的剪切模量没有变化。W2组或CON组中双关节绳肌的剪切模量没有显著变化。W2组和W3组的等长扭矩（分别为20.3%和26.2%）和半膜肌体积（分别为5.7%和7.4%）显著增加。
当以相对较高的每周频率和较高的总训练量进行LL仅离心抗阻训练时，特定肌肉的被动僵硬度可能会长期降低。我们的训练方式可能是一种在增加肌肉力量和尺寸的同时降低肌肉被动僵硬度的有前景的策略。
